This invention related generally to voltage regulators, and relates in particular to voltage regulators for use in systems that employ multiple voltage levels.
In certain electronic system such as digital signal processing systems that run on battery power, it is desirable to permit the power supply to provide full power during normal operation, yet provide a reduced power level when the circuit is in an idle state.
Dual power supplies may provide both a high voltage (e.g., 1.5 volts) and low voltage (e.g., 0.9 volts) at all times, and may provide switching between the voltage sources for operation of the system as required. Such an approach, however, may not be energy efficient as it must always provide both voltage potentials as well as the required current.
Another approach may involve changing the output voltage of the power supply responsive to the power needs of the system during operation. This approach, however, may result in power surges or spikes when the change occurs. Moreover, many power supplies include a capacitor at the output stage, and changing the output voltage may require time for the capacitor to change its charge accordingly, particularly when changing from the high to the lower output voltage.
There is a need, therefore, for a more efficient and economical voltage regulator for use in a multi-voltage power supply system.